JPS61211712A - Ac switching circuit - Google Patents

Abstract

PURPOSE:To simplify a whole circuit by constituting at least one of a main switching circuit and a switching circuit for a fly wheel of a saturable reactor. CONSTITUTION:When a controlling circuit 16 outputs a controlling signal, a main switching circuit 10 and a switching circuit for flywheel 14 become on and off alternately. For instance, in a half period of an AC power source 3, when the controlling signal changes to high level, the main switching circuit 10 becomes on and current flows to a load 1. When the controlling signal becomes low level, the switching circuit 14 for flywheel becomes on and flywheel current of the load 1 flows in the switching circuit 14 for flywheel. At this time, as a saturable reactor B has inductance, current flowing there increases with slight delay. No large trouble will occur even if synchronism of on and off of the two circuit is imperfect.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an alternating current switching circuit that switches alternating current supplied to a load at a higher speed than a 9S power supply to change its conduction rate.

(Background of the Invention) A main circuit is formed by connecting a load, a main switching circuit, and an AC power source in series, and a flywheel switching circuit and a flywheel switching circuit are connected to the load at a higher frequency than the AC power source. AC switching circuits that alternately switch are considered.

FIG. 3 shows a conventional circuit of this type. In the circuit of FIG. Wheel switching circuits 4 are connected in parallel. Here, the main switching circuit 2 and the flywheel switching circuit 4 are formed by a bridge consisting of a diode D and a transistor TR. In the circuit shown in FIG. 2B, the main switching circuit 2A and the flywheel circuit 4A are formed by connecting a series circuit of a diode D and a transistor TR in antiparallel.

Such conventional switching circuits 2, 2'A.

When a semiconductor switching element is used as in the case of 4.4A, there is a problem that the circuit becomes complicated.

In particular, this type of semiconductor switching element always has a turn-off time, so interlocks should be taken into account to prevent the semiconductor switching elements of the main switching circuit and the flywheel switching circuit from turning on at the same time. This makes the circuit even more complicated. Further, in this case, a high-speed semiconductor switching element must be used, but there is also the problem that such an element is very expensive.

(Objective of the Invention) The present invention was made in view of the above circumstances, and an object thereof is to provide an AC switching circuit that allows the circuit to be configured very easily and eliminates the need to use expensive semiconductor switching elements. shall be.

(Structure of the Invention) According to the present invention, this object is to connect a load, a main switching circuit, and an AC power supply in series to form a child circuit, and connect a flywheel switching circuit in parallel to the load. , an AC switching circuit configured to alternately switch the upper switching circuit and the flywheel switching circuit at a higher frequency than the AC power supply, wherein at least one power of the main switching circuit and the flywheel switching circuit is provided by a saturable reactor; This is achieved by an AC switching circuit characterized in that it is formed.

(Embodiment) FIG. 1 is a circuit diagram showing an embodiment of the present invention. In this figure, the main switching circuit 10 consists of four diodes and MO3
The flywheel switching circuit 14 is composed of a ring A consisting of type FET 1.2, and the flywheel switching circuit 14 is a saturable reactor B.
It consists of

In other words, this saturable reactor B has a load winding a wound around a core and a control winding S, and the load winding a is connected in parallel to a load l. 16 is a control circuit that detects a change in the current flowing through the load 1 from a change in the voltage across the load 1, and sends a control signal to the gate of the FET 12 to turn it on and off at a frequency higher than the frequency of the AC power source 3. . Further, this control signal is inverted by an inverter 18 and input to the control winding of the saturable reactor B.

In this embodiment, when the control circuit 16 outputs a control signal, the main switching circuit 10 and the flywheel switching circuit 14 are turned on and off alternately. For example, in one half cycle of the AC power supply 3, when the control signal changes to a high level, the main switching circuit 10 is turned on, and current flows to the load l. When the control signal becomes low level, the flywheel switching circuit 14 is turned on, and the load 1 is turned on.
flywheel current flows through this flywheel switching circuit 14. At this time, since the saturable reactor B forming the flywheel switching circuit 14 has an interface, the current flowing therein increases with a slight delay. Therefore, even if the on/off synchronization between the switching circuit diagram and the flywheel switching circuit 14 is incomplete, no major inconvenience occurs. In other words, a complicated interlock circuit is no longer required, the circuit configuration becomes simpler, and
There is no need to use expensive semiconductor switching elements.

FIG. 2 is a circuit diagram showing another embodiment of the present invention. In this embodiment, both the main switching circuit 10A and the flywheel switching circuit 14A are saturable reactors.
It is composed of According to this embodiment, the control circuit 16A can be completely isolated from the main circuit by detecting changes in the load current through an isolation transformer, etc., and the overall circuit configuration is also very simple. becomes simple.

Note that, of course, in the present invention, only the main switching circuit may be configured with a saturable reactor. In addition, if the core of a saturable reactor is made of amorphous magnetic alloy such as iron, cobalt, and nickel alloy, the magnetic flux reduction is high, the coercive force is small, and the core loss is also small, so the excitation current is small. This makes the circuit smaller and more efficient.

(Effects of the Invention) As described in 1- below, the present invention comprises at least one of the main switching circuit and the flywheel switching circuit using a saturable reactor. The interlock circuit becomes unnecessary or can be made very simple, and the entire circuit can be simplified. Another advantageous effect is that there is no need to use expensive high-speed semiconductor switching elements.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention, FIG. 2 is a circuit diagram of another embodiment, and FIG. 3 is a circuit diagram of a conventional AC switching circuit. l...Load, 3...AC power supply, to, IOA...'' Nisshinting circuit, 14.14
A...Flywheel switching circuit, B...iIf saturation reactor.

Claims (2)

[Claims] (1) A load, a main switching circuit, and an AC power source are connected in series to form a main circuit, while a flywheel switching circuit is connected in parallel to the load, and the main switching circuit and the flywheel switching circuit are connected in parallel. An AC switching circuit configured to alternately switch at a higher frequency than the AC power supply, characterized in that at least one of the main switching circuit and the flywheel switching circuit is formed of a saturable reactor. (2) The AC switching circuit according to claim 1, wherein the saturable reactor has a core made of an amorphous magnetic alloy.